Function MakeSDF

core/sdf.cpp:116–186

}

void MakeSDF(const uint32_t* img, uint32_t w, uint32_t h, float* output)
{	
	const float scale = 1.0f / max(w, h);

	std::vector<Coord2D> queue;

	// find surface points
	for (uint32_t y=0; y < h; ++y)
	{
		for (uint32_t x=0; x < w; ++x)
		{
			if (EdgeDetect(img, w, h, x, y))
			{
				Coord2D c = {(int)x, (int)y, 0.0f, (int)x, (int)y};
				queue.push_back(c);
			}

			output[y*w + x] = FLT_MAX;
		}
	}

	std::make_heap(queue.begin(), queue.end());

	while (!queue.empty())
	{
		std::pop_heap(queue.begin(), queue.end());

		Coord2D c = queue.back();
		queue.pop_back();

		// freeze coord if not already frozen
		if (output[c.j*w + c.i] == FLT_MAX)
		{
			output[c.j*w + c.i] = c.d;

			// update neighbours
			int xmin = max(c.i-1, 0), xmax = min(c.i+1, int(w-1));
			int ymin = max(c.j-1, 0), ymax = min(c.j+1, int(h-1));

			for (int y=ymin; y <= ymax; ++y)
			{
				for (int x=xmin; x <= xmax; ++x)
				{
					if (c.i != x || c.j != y)
					{
						int dx = x-c.si;
						int dy = y-c.sj;

						// calculate distance to source coord
						float d = sqrtf(float(dx*dx + dy*dy));

						Coord2D newc = {x, y, d, c.si, c.sj};
						queue.push_back(newc);
						std::push_heap(queue.begin(), queue.end());
					}
				}
			}	
		}